U.S. patent number 4,466,480 [Application Number 06/375,217] was granted by the patent office on 1984-08-21 for temperature control apparatus for a motor vehicle air conditioner.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Kenichi Chonan, Tosikazu Ito.
United States Patent |
4,466,480 |
Ito , et al. |
August 21, 1984 |
Temperature control apparatus for a motor vehicle air
conditioner
Abstract
A temperature controlling apparatus is provided for use in
systems such as a motor vehicle air conditioner. In the temperature
controlling apparatus, a cycling clutch and a re-heated air mixing
system are selectively used in accordance with the environmental
condition. The cycling clutch system temperature control is
effected in summer season to control an operating period of time of
a compressor, and the re-heated air mixing system temperature
control is effected in spring or autumn season to dehumidify the
air and in winter season by means of an air mixing door after
stopping the compressor thereby controlling an amount of the intake
air which is to be re-heated.
Inventors: |
Ito; Tosikazu (Ibaraki,
JP), Chonan; Kenichi (Katsuta, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
13331953 |
Appl.
No.: |
06/375,217 |
Filed: |
May 5, 1982 |
Foreign Application Priority Data
|
|
|
|
|
May 6, 1981 [JP] |
|
|
56-66990 |
|
Current U.S.
Class: |
165/202; 165/291;
165/297; 165/43; 62/226; 62/229; 62/323.4 |
Current CPC
Class: |
B60H
1/3207 (20130101); G05D 23/20 (20130101); G05D
23/1917 (20130101) |
Current International
Class: |
B60H
1/32 (20060101); G05D 23/20 (20060101); F25B
029/00 () |
Field of
Search: |
;165/12,28,30,40,42,43
;62/226,229,244,323.4 ;237/2A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2939954 |
|
Apr 1980 |
|
DE |
|
55-1215 |
|
Jan 1980 |
|
JP |
|
Primary Examiner: Hart; Douglas
Attorney, Agent or Firm: Antonelli, Terry & Wands
Claims
What is claimed is:
1. A temperature control apparatus for use in a motor vehicle air
conditioner, the temperature control apparatus comprising:
an evaporator means; a heater core means for re-heating air cooled
by said evaporator means; a compressor means for circulating a
refrigerant through said evaporator means; an air mixing means for
controlling a ratio of an amount of cooled air passing through said
heater core means for re-heating to an amount of cooled air
bypassing said heater core means; a first temperature controlling
circuit means for controlling a position of said air mixing means
to maintain a temperature of a vehicle chamber at a desired level
and for stopping said compressor means immediately prior to said
evaporator means being frozen; and a second temperature controlling
circuit means for controlling an operating period of time of said
compressor means to maintain the vehicle chamber temperature at
said desired level; and means for selectively switching said first
and second temperature controlling circuit means in dependence upon
operating conditions of said air conditioner.
2. A temperature control apparatus according to claim 1, further
comprising means for stopping a heating said heater core means when
said second temperature controlling circuit means is selected by
said switching means.
3. A temperature control apparatus according to claim 1, wherein
the operating conditions of said switching means include an outdoor
temperature, said switching means being adapted for selectively
switching over said first and second temperature controlling
circuit means in response to an output of an outdoor temperature
sensor.
4. A temperature control apparatus according to claim 1, wherein
the operating conditions of said switching means include one of a
first demand for cooling said vehicle chamber and a second demand
for heating said vehicle chamber, said switching means being
adapted for selectively switching over said first and second
temperature controlling circuit means in accordance with an output
having a sign produced from a decision means for deciding said
first demand.
5. A temperature control apparatus according to claim 4, wherein
said decision means decides as to whether a demand for said vehicle
chamber is said first or second demand to thereby generate an
output having a sign.
6. A temperature control apparatus according to claim 1, wherein
said means for selectively switching includes a means for detecting
a physical quantity representing an operating condition of the air
conditioner and for producing an electric signal corresponding to
the detected quantity, and a switching device operable in response
to a predetermined electric signal from said detecting means.
7. A temperature control apparatus according to claim 6, wherein
said first temperature controlling circuit means includes a
temperature sensor means for sensing a control temperature of
freezing of said evaporator means so as to enable the stopping of
said compressor means in response to a predetermined output of said
temperature sensor means.
8. A temperature control apparatus according to claim 7, wherein
said temperature controlling circuit means is adapted to maintain
the vehicle chamber at the desired level while said air mixing
means is set a position at which an amount of cooled air bypassing
the heater core means is a maximum.
9. A temperature control apparatus for use in a motor vehicle air
conditioner, the temperature control apparatus comprising:
an evaporator means; a heater core means for re-heating air cooled
by said evaporator means; a compressor means for circulating a
refrigerant through said evaporator means; means for detecting an
operating state of said evaporator means; means for generating a
reference signal corresponding to a state of said evaporator means
immediately before said evaporator means is frozen; a first
temperature controlling circuit means for comparing an output
signal of said detecting means with said reference signal to
thereby stop an operation of said compressor means immediately
before said evaporator means is frozen; air mixing means for
controlling a ratio of an amount of cooled air passing through said
heater core means for re-heating to an amount of cooled air
bypassing said heater core means; a position of said air mixing
means being controlled to maintain a temperature of a vehicle
chamber at a desired level; a second temperature controlling
circuit means for controlling an operating time of said compressor
means; means for fixing said air mixing damper at such a position
that an amount of the cooled air bypassing said heater core means
becomes maximum; means for selectively switching said first and
second temperature controlling circuit means in accordance with
operating conditions of the air conditioner; an adjustment means
for relatively changing comparison levels of the reference signal
and the output signal of said detecting means in said first
temperature controlling circuit means to thereby stop the operation
of said compressor means at a time point appropriately earlier than
immediately before when said evaporator means is frozen, said
comparison levels being adjusted to control the operating period of
said compressor means to thereby maintain the vehicle chamber
temperature at a desired level.
10. A temperature control apparatus according to claim 9, wherein
said means for selectively switching includes a means for detecting
a physical quantity representing an operating condition of the air
conditioner and for producing an electric signal corresponding to
the detected quantity, and a switching device operable in response
to a predetermined electric signal from said detecting means.
11. A temperature control apparatus according to claim 10, wherein
said first temperature controlling circuit means includes a
temperature sensor means for sensing a critical temperature of
freezing of said evaporator means so as to enable the stopping of
said compressor means in response to a predetermined output of said
temperature sensor means.
Description
The present invention relates generally to a temperature control
apparatus for use in a motor vehicle air conditioner, and more
particularly, to a temperature control apparatus of the so-called
re-heated air mixing system for use in a motor vehicle air
conditioner, wherein the intake air is cooled and dehumidified
through an evaporator, with a ratio of an amount of the cooled air
bypassing a heater core with respect to an amount of the cooled air
passing through the heater being controlled by means of an air
mixing door so that only the amount of cooled air passing through
the heater is re-heated by the heater, whereby the temperature of
discharge air can be controlled.
In a prior-art temperature control apparatus of re-heat air mixing
system for use in a motor vehicle air conditioner, since an amount
of the air cooled and dehumidified which passes through a heater
for heating is controlled by means of an air mixing door to thereby
control a temperature of the discharge air, the heater must be
actuated even in summer season for temperature control.
More specifically, the cooled and dehumidified air has a
temperature of 0.degree. C. to 10.degree. C. In order to raise a
temperature of the cooled air up to a level corresponding to a
desired set temperature in the vehicle chamber, the heater must be
activated to re-heat a portion of the cooled air.
This means that the compressor in the motor vehicle air conditioner
must be driven additionally by an amount of energy corresponding to
the energy used in re-heating the portion of the cooled air by the
heater, in summer season.
Accordingly, it is an object of the present invention to minimize
an operating period of time of the compressor and therefore the
engine load, especially, in summer season to thereby reduce the
fuel cost of a motor vehicle equipped with an air conditioner.
The feature of present invention resides in that a temperature
controlling system can be switched over to either the cycling
clutch system or re-heated air mixing system in accordance with
operating conditions, so that the cycling clutch system temperature
control is effected in summer season to control an operating period
of time of the compressor, and the re-heated air mixing system
temperature control is effected in spring or autumm season to
dehumidify the air and in winter season by means of an air mixing
damper after the compressor is stopped thereby controlling the
amount of intake outdoor air which is to be re-heated.
The above and other objects and advantages of the present invention
will become clear from the following description with reference to
the accompanying drawing, in which:
The single FIGURE is a block diagram for illustration of a
temperature control apparatus for use in a motor vehicle air
conditioner in accordance with an embodiment of the present
invention.
Referring to the drawing, a ventilating line 1, comprised of ducts
and casings, is provided at its inlet portion with a blower or fan
2 which is driven by a motor.The air brought into the ventilating
line 1 by the blower 2 will pass through an evaporator 3 disposed
within the ventilating line 1. The cooled air flowing through the
evaporator 3 will be divided into two flows by an air mixing door
6, that is, an air flow through a heater core 4, and an air flow
bypassing of the core 4.
On the other hand, an inlet-air switching door 5 is provided to
selectively bring into the ventilating line 1 one of the
above-mentioned two different flows of the air within the vehicle
chamber, the air outside of the vehicle, i.e., outdoor air, and the
mixture thereof.
Downstream of the heater core 4, the ventilating line 1 is branched
into an outlet port, 1a, through which the air is discharged upward
within the vehicle chamber, and an outlet port 1b through which the
air is discharged downward within the vehicle chamber.
At the branched point between the outlet ports 1a and 1b, a
diverting damper 7 is disposed to control the air diverting ratio
between the outlet ports 1a and 1b.
Further, the duct connecting the diverting door 7 and the outlet
port 1b has at its intermediate portion an additional ventilating
duct branched to a defrosting outlet port 1c. The additional duct,
in turn, is provided at its branching portion with a defrosting
door 8. The air discharged from the defroster port 1c will be
directed toward the windshield in front of the vehicle.
A temperature sensor 9, mounted on an instrument panel within the
vehicle, will detect a typical temperature in the vehicle chamber
in the form of an output voltage signal and sent it to a first
control circuit 10. The first control circuit 10 will also receive
an output voltage signal representative of the opening degree of
the air mixing door 6 from a potentiometer 12.
The first control circuit 10 will calculate the opening or closing
degree of the mixer door, 6 on the basis of its input voltage
signals and control a transducer 13 according to its output voltage
signal representative of the calculation result, whereby the
temperature in the vehicle chamber is set at a desired set
level.
When it is desired to reduce the amount of air flowing through the
heater 4 to decrease the discharge air temperature, the transducer
13 will be energized so as to increase the negative pressure
supplied to an actuator 14 to thereby pull the air mixing damper 6
by a set amount up to its dotted-line position.
Conversely, if it is desired to increase an amount of the air
flowing through the heater 4 to raise the discharge air
temperature, then the transducer 13 will be deenergized so as to
increase an amount of outdoor air supplied to the actuator 14 to
thereby pull the damper 6 by a set mount up to its solid-line
position. A spring (not shown) provides the necessary force for
returning the door to its original position.
A solenoid valve 15 disposed within a fluid passage between the
transducer 13 and the actuator 14, and, when energized, the valve
15 will block the fluid supplied from the transducer 13 and apply
the negative pressure from a negative pressure source directly to
the actuator 14. Under this condition, the air mixing door 6 will
be kept at the dotted-line position.
When deenergized, on the other hand, the solenoid valve 15 will
block the negative pressure from being applied to the actuator 14
and instead supply the fluid from the transducer 13 to the actuator
14.
A temperature sensor 16 is used to detect or sense a temperature of
the cooled air supplied from the evaporator 3 in the form of an
output voltage signal and apply the signal to a second control
circuit 17.
A rheostat 18 for temperature setting is controlled by a lever 23
to set a temperature of the cooled air from the evaporator 3. An
output voltage signal from the rheostat resistor 18 is sent to the
second control circuit 17.
The second control circuit 17 will function to decide as to whether
a compressor 19 is driven or stopped on the basis of both the input
signals from the sensor 16 and the rheostat 18, and according to
the decision result, it is decided whether an electromagnetic
clutch 19a is energized or deenergized, to thereby drive or stop
the compressor 19 and set the evaporator 3 exit temperature at a
desired set level.
For example, when it is required to lower the cooled air
temperature from the evaporator 3, the electromagnetic clutch 19
will be energized to drive the compressor; whereas if it is desired
to raise the cooled temperature, then the clutch will be
deenergized to stop the compressor.
Ambient temperature switches 20 and 20' are interlocked to each
other and both function to switch to contact "a" when the ambient
temperature exceeds 25.degree. C. and switch to contact "b" when
the temperature is not higher than 25.degree. C.
Another electromagnetic valve 21 is placed in a negative pressure
passage between the negative pressure source and an actuator of a
warm water valve 22. When energized, the valve 21 will apply the
negative pressure to the warm-water valve actuator to open the
associated valve 22. If deenergized, the valve 21 will apply the
atmospheric pressure to the actuator to close the associated
warm-water valve 22.
In this way, the warm-water valve 22 will control an amount of the
warm water supplied to the heater core 4 through its open or close
operation.
When the ambient temperature switches 20 and 20' are at the "b"
contact positions, the electromagnetic valve 21 will be energized
so as to open warm-water valve 24 and the second control circuit 17
will receive a voltage drop signal across a fixed resistor 24
instead of the output voltage of the rheostat 18. At this time, the
second control circuit 17 and the fixed resistor 24 together form
an anti-freezing circuit for the evaporator 3.
The value of the fixed resistor 24 is selected in association with
the output voltage of the sensor 16 in such a manner that the
second control circuit 17 generates a compressor stop signal only
when the temperature of the cooled air at the evaporator outlet
drops below 0.degree. C., namely, a critical temperature of
freezing of the evaporator.
With the ambient temperature switches 20 and 20' at the "a" contact
positions, the electromagnetic valve 15 will be energized so as to
keep the air mixing door 6 at its dotted-line position and at the
same time, the electromagnetic valve 21 will be deenergized so as
to close the warm water cock 22. Further, the control circuit will
receive the output voltage of the rheostat resistor 18.
Therefore, if the ambient temperature rose to 25.degree. C. or
above, for example, as in the summer season, then the air mixing
door 6 will be kept at the dottedline position so that the second
control circuit 17 causes the compressor 19 to controllably be
turned on or off, whereby the temperature of the cooled air at the
evaporator 3 outlet will be adjusted to a level set by the rheostat
18 and thus the temperature of the air discharged into the vehicle
chamber can be adjusted.
Since this eliminates re-heating operation by the heater 4, the
operating time of the compressor 19 will be correspondingly
reduced.
At the same time, the temperature control apparatus is arranged so
as to stop the supply of warm water into the heater 4 in the
illustrated embodiment, and thus the cooled air is prevented from
being heated by the heater 4 during its passage around the heater
4.
On the other hand, when the ambient temperature drops below
25.degree. C., for example, as in the winter season, the output
signal from the first control circuit 10 will cause the opening
degree of the air mixing door 6 to be controlled, whereby the
discharge air temperature can be adjusted.
Although the above explanation has been made in connection with the
case where switching of the switches 20 and 20' is effected
according to the ambient temperature, it will be understood that
the invention is not limited to the particular embodiment but
covers all other possible modifications, alternatives and
equivalent arrangements included in the scope of appended
claims.
For example, the temperature control apparatus can be arranged so
that the apparatus decides as to whether it is desired to increase
or decrease the temperature in the vehicle chamber, i.e., cool
demand or heat demand, and so that the ambient temperature switches
20 and 20' are moved to the "a" contact positions for the cool
demand to put the apparatus under the cycling clutch system
temperature control; whereas the switches 20 and 20' are moved to
the "b" contact positions for the heat demand to put the apparatus
under the re-heated air mixing system temperature control.
The demand deciding means may basically comprise an A/D converter
for receiving both the output of the vehicle chamber temperature
sensor 9 and the output of the set-temperature detecting
potentiometer 11 to convert to corresponding digital signals, as
well as an arithmetic unit for performing proportional/integral
operations on the both digital output signals from the A/D
converter under predetermined programs to calculate the
corresponding cooling or heating demand amount.
In this connection, current variations in a phototransistor by
solar radiation light may be converted to a voltage signal and
further to a digital signal, and at the same time the output of the
ambient temperature sensor may be converted to a digital signal, to
thereby add both the digital signals as a correction value to the
digital signal indicative of the set temperature, if desired.
The output of the arithmetic unit has a plus or minus sign. If the
output has a minus sign, then the temperature control apparatus
will operate as a cooling one until the cool demand amount is
minimized. While, when the output has a plus sign, the apparatus
will operate as a heating one until the heat demand amount is
minimized.
The arithmetic unit may be replaced by the first control circuit
10. In that case, the output of the arithmetic unit will be sent,
when having a plus sign, to the transducer 13 to control the air
mixing door 6 according to the output amount of the transducer 13
and thus control the temperature of the discharge air. When the
output of the arithmetic unit has a minus sign, on the other hand,
the temperature control apparatus is arranged so that the output
with a minus sign will cause a relay to be energized to switch its
relay contacts into the corresponding contact positions which have
the same function as those of the switches 20 and 20', thereby
putting the apparatus in the above-mentioned temperature control
mode of the cycling clutch system.
In lieu of the ambient temperature switches 20 and 20', such an
arrangement may be employed that a thermistor is used to detect the
ambient temperature, and an electronic circuit is controlled
according to the output of the thermistor to actuate a relay so
that contacts in the relay will be switched into proper positions
corresponding to the same function as the switches 20 and 20'.
With the arrangement of the present invention a temperature control
system can be switched over such that the temperature control is
effected by means of turning on and off of the compressor in the
summer season and effected by means of adjusting the air mixing
door while the compressor is operated at a maximum rate of
operation. However, since the evaporator quickly reaches a critical
temperature of freezing in conditions of a low heat load, the
actual rate of operation is fairly low in spring, autumn, and the
winter season, whereby the fuel cost of a vehicle mounted with the
air conditioner according to the present invention can be reduced
without losing the dehumidifying function frequently necessary in
spring or autumn season, while reducing the operating period of
time of the compressor in summer season.
* * * * *